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Polyvinylidene fluoride microporous film preparation method

A technology of polyvinylidene fluoride and polyvinylidene fluoride resin, which is applied in the field of preparing polyvinylidene fluoride microporous membranes and thermally induced phase separation, which can solve the difficulty of extraction and recovery of ternary diluents and other issues to achieve a good penetration effect

Active Publication Date: 2009-11-04
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this paper, a high-temperature solvent and a non-solvent are mixed as a compound diluent of vinylidene fluoride resin. The PVDF microporous membrane prepared has an ideal uniform sponge-like cross-sectional structure and high strength and pure water flux, and solves the problem of Solved the difficult technical problem of ternary diluent extraction and recovery

Method used

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  • Polyvinylidene fluoride microporous film preparation method
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  • Polyvinylidene fluoride microporous film preparation method

Examples

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preparation example Construction

[0024] The method for preparing PVDF microporous membrane of the present invention, carries out as follows:

[0025] 1) Mix polyvinylidene fluoride resin with compound diluent, wherein the mass percentage of polyvinylidene fluoride is 20%-60%, and the corresponding mass percentage of compound diluent is 80%-40%;

[0026] 2) Put the mixture in step 1) into a stirred tank, heat up to 180°C-220°C to form a homogeneous solution, and let it stand for defoaming;

[0027] 3) Scrape-coat the homogeneous solution in step 2) on the support net to form a flat plate or spin it into a hollow fiber through a spinneret and immerse it in the cooling liquid to separate the polyvinylidene fluoride from the composite diluent and solidify Form flat membrane or hollow fiber membrane;

[0028] 4) extracting the composite diluent in the membrane obtained in step 3) with an alcohol or ether extractant to obtain a polyvinylidene fluoride flat microporous membrane or a hollow fiber microporous membran...

Embodiment 1

[0037] Embodiment 1: be 20% by mass percentage, the PVDF resin that weight-average molecular weight is 100,000, mass percentage is the compound diluent of 80% (high temperature solvent methyl benzoate mass percentage is 90% in the compound diluent, non-solvent hexadiene Dioctyl acid (10% by mass percent) was put into a stirred tank and heated to 180° C., stirred and mixed to form a homogeneous solution, and left to stand for 2 hours. The homogeneous solution was scraped onto a support net to form a flat plate with a thickness of 200 μm, and immersed in a water bath at 0° C. to separate and solidify the solution to form a film. The cured flat film was extracted with ethanol and dried.

[0038] The cross-section of the membrane is a uniform spongy structure with a breaking strength of 2.7MPa, a breaking elongation of 30%, and a pure water flux of 3,136L / (m 2 ·.hr.·0.1MPa).

Embodiment 2

[0039]Embodiment 2: be 25% by mass percent, the PVDF resin that weight-average molecular weight is 800,000, mass percent is the compound diluent of 80% (in the compound diluent, high-temperature solvent triacetin mass percent is 30%, non-solvent benzyl alcohol The mass percentage is 70%) in a stirred tank and heated to 180° C., stirred and mixed to form a homogeneous solution, and left to stand for 2 hours. The homogeneous solution was extruded through the spinneret under a certain pressure to form a hollow fiber (outer diameter 1.5mm, inner diameter 0.9mm), and then directly immersed in a water bath at 80°C to separate and solidify the solution. The cured PVDF hollow fiber microporous membrane was extracted with ethanol and then dried.

[0040] The cross-section of the membrane is a uniform spongy structure with a membrane breaking strength of 3.1MPa, a breaking elongation of 30%, and a pure water flux of 2,672L / (m 2 ·.hr.·0.1MPa).

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Abstract

The invention relates to a polyvinylidene fluoride microporous film preparation method by thermally induced phase separation, particular to a polyvinylidene fluoride microporous film preparation method by mixing the high temperature solvent and nonsolvent of the polyvinylidene fluoride in certain proportion to form a compound thinner. The method includes the following steps: polyvinylidene fluoride with the mass percentage of 20-60% and a corresponding compound thinner with the mass percentage of 80-40% are added into a stirring kettle, high-temperature digestion and standing deaeration are carried out in sequence to obtain homogeneous casting solution; the casting solution is directly coated on a supporting net by direct knifing to be planar or is spun by a spinneret to be hollow fibrillar, then the casting solution is dipped into cooling fluid for split phase solidification; and the thinner contained in solidification products is extracted, thus obtaining the polyvinylidene fluoride microporous film. The polyvinylidene fluoride microporous film prepared by the invention is high in film strength and large in water flux with the sections which have a uniform and run-through spongelike structure.

Description

technical field [0001] The invention belongs to the field of polymer material science and technology, and relates to a method for preparing a polyvinylidene fluoride microporous membrane by a thermally induced phase separation (TIPS) method, especially by combining a high-temperature solvent of polyvinylidene fluoride with a non-solvent A method for preparing a polyvinylidene fluoride microporous membrane by mixing in a certain proportion to form a composite diluent. Background technique [0002] Membrane separation technology is an effective separation technology, which has the characteristics of simple equipment, convenient operation, energy saving and environmental protection. Since the separation membrane needs to withstand the cleaning of strong oxidizing, strong acid and alkali chemicals during the application process, it is necessary for the membrane material to have excellent chemical stability. As a thermoplastic semi-crystalline polymer, vinylidene fluoride (PVDF)...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34B01D69/12B01D69/08
Inventor 王晓琳马恒宇田野林亚凯唐元晖马文中杨健
Owner TSINGHUA UNIV
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